Electrothermal protector.



No. 870,714. PATENTED NOV. 12, 1907.

F. B. 000K.

ELEGTROTHERMAL PROTECTOR.

APlJGATION FILED PEB. l5, 1907.

MVQW /af Y- @M vf-Mh@ FRANK B. COOK, OF CHICAGO, ILLINOIS.

ELECTROTHERMAL PROTECTOR.

Specification of Letters Patent.

Patented Nov. 12, 1.907.

Appiano.. ned february 15.1907. serial No. 357.580.

To lall whom it may concern:

lBe it known that I, FRANK B. Coon, a citizen of the United States of America, residing at Chicago, in the county of Cook and State of Illinois, have invented a new and useful Electrothermal Protector, o which the following is a specification, reference being had to the accompanying drawings, illustrating same.

My invention relates to electrical protectors used for protecting electrical circuits and apparatus from abnormally large currents o electricity, the form herein illustrated being adapted in particular for telephone systems to protect the lines and delicate apparatus thereof from injurious currents of electricity slightly in excess of the normal, which currents are generally termed sneak currents.

The principal objects of my invention are to provide a protector of the longitudinally-operable type which is absolutely fire proof; to provide. such a protector in which the heating means is in the Aform ofa homogeneous body of resistance material; to provide an electrothermal protector which is a complete unit in itself and which contains spring operating means for operating same, whereby they protector may be operated Without depending upon' spring operating means apart from the protector unit; to provide an electro-thermal protector having an openable joint in the circuit normally held against opening by a non-conducting cement applied within the joint in such a manner as to not materially increase the resistance of the joint; to construct such a protector 4so that it willbe very uniform and thoroughly reliable in itsvoperation; and to provide simplicity of construction and durability in such a protector.

Other objects will be apparent from the following when `the thermal protector operates and opens the circuit, the high-voltage current will form an arc at the protector,where the circuit is opened only a slight distance, and the current will thus continue to flow through the protector. The arc thus established inthe protector will set re to the infiammable inclosing shell, which will in turn set fire to other protectors directly above this protector, 4and thereby sometimes burn out or injure a whole strip of protectors and thus `throw a number of lines out of service and also cause considerable damage by fire.

In my present invention I have provided an electroi thermal protector which operates upon excessive heat- Ving to allow circuit-controlling means to control suitable circuits, but which does not open the circuit at the protector, thus doing away with the formation of an arc at the protector. In this protector I also do away with the coil of fine wire generally provided as heating means in such protectors, and employ herein a body of powdered resistance material suitably held in shape and which is capable of standing a considerable increase in current above the normal. Then I construct this protector with' a metallic casing inclosing same and thereby do away with the ordina-ry inammable inclosing shell usually employed.

I will now more particularly describe my invention by reference to the accompanying drawings in which,'-

Figure 1 is a side elevation of the complete protector unit; Fig. 2 is a longitudinal cross-sectional View of the protector shown in Fig. l, with portions shown in elevation; Fig. 3 is an end elevation of Fig. 1; Fig. 4 is a side elevation of the coil spring preferably employed in the protector of Figs. l and 2 for keeping the circuit' through the protector closed when same operates; Fig. 5 is a side elevation of the coilspring of Fig. 4, compressed as in the protector of Fig. .2 when saine is set for operation; and Fig. 6 is a side elevation of the protector of Figs. l and' 2, showing the protector after same has operated, a portion of the exterior metallic shell being shown in cross-section to show the position of the coil spring when the protector is operated. I

Like characters refer to like parts in the several figures. l

The heating element l, preferably comprising a- `suitable powdered resistance material pressed into a pill, is inclosed in the metallic shell orrcup 2 and insulated from the sides thereof' by a thin piece of insulating material 3. The heating element 1 is shown, described and claimed in my copending application for Letters Patenton electro-thermal protector, Serial No. 316,153, filed May 10, 1906. Against the outer end of the heating element 1 is placed a disk 4 to make electrical connection with the element 1. A terminal portion 5, provided with a large end portion 6, is placed against contacts 7 7 on the disk 4 so as to make good electrical connection therewith and at the same time provide an air space 8 which keeps the hat produced i n the protector from being conducted to the terminal 5. The end portion 9 of the metallic cup 2 is formed over susv ioo

around the end portion 6 of terminal 5, preferably as terminal 10 is provided with a cup-shaped portion ,1I l

adapted to fit over the vmetallic cup 2 and make shaped portions2 and 11, and preferablyy extending all' electrical connection therewith." Between the cupover-the contact surface therebetween, is'placed a thin film 17 of 'heat-susceptible, non-conducting,ce inenting material, preferably a ycompdund'oi Venice turpentineand guinshellac, to cement` the two c upshaped portions 2 andvl1V together. "The Iiilmv of ce- 'menting material between the portions'v2 and 11 is thin enough so as lnotto materially interfere with' the metallic contact between these-.two parts. In practice it lhasbeen demonstrated that ythe resistance through this cementedijoint is onlya very lsmall fraction oi an ohm., and' that -the joint so made7 in the type of pro- 'tecto illustrated, will normally stand a pull hf 100y .1'5

pounds o if more. The compound of Venice turpentine .and gum. shellac used, softens at about 150 degrees F.

andallows the cups 2 and 11'to be readily separated. The cupfshaped portions 2 and 11 are preferably conically shaped so that they will tightly fit each other and 10 are provided with s mall neckl portions 12 and 13.

' Which prevent anyfconsiderable conduction of heat to v element 1, end ldfoi cup 2,. the conical portion of cupv v2, the cementing'material between portions 2 and 11,

the said terminals. Theterminals-5 and 10 are preierably provided with the usual annular. recesses therein 'to Ait suitable spring members in the ordinary telle-i phone protective apparatus. The coil spring 14 of Fig. 4 'is pla ced within the cup portion .11, preferablyl as shown in Fig. 2, the smaller end of spring 14 graspingthe knob 15,0n the endoi cup 2 and the larger end of spring 14 being forced down into the smaller portion -of cup -11 and being'somewhat compressed thereby.

The coil spring 14z makes electrical connection between the lmetallic cups 2 and 11 and thereby prevents the circuit through the protector from being opened when the protector is operated as shown in Fig..6. This coil spring 14 is compressed as shown in Fig. 5, when the protector is set for operationas shown in Fig. 2, and isvprefer'ably strong enough to operatethe parts of the protector from the position shown in Fig. 2 to the position shown in Fig.v 6, without any other spring means to assist it. Thus in addition tokeepingthe circuit through the protector closed, the coil spring 14 also tends to operate the protector when same is suciently' heated. f

The circuit through the 'protector' is from terminal 5, A

lthrough neck portion 12, contacts 7 75 disk 4, heating the conical portionloi cup 11, neck portion 13gto terminal 10. Aiiabnorinally. large current traversing this circuit heat y'the resistanceelement.` 1. The heat thus produced,- tallic cup 2 to tlifel cemented jointbetween theV cups `2 and 1 1 Where itsoitensthe cementing material and allows the cups 2 and ll-to separate as shown in=Fig. 6.

The spring '14,011 springs connected with terminals 5 and l0, or both',y now operate the protector from the position shown in Fig. 2 to the position shown in Fig. 6.

and4 thereby allow suitable circuits to be controlled in any suitable manner. 1t is not thought to be neces-` s'mhm the device isconducted by the me'-y apparatus of this character.

manner and the parts pressed-together again as shown in Fig. 2, and allowed to cool, whereupon the cementing material17 will recement the cups 2 and 11 togethe r sition ior another operation.

The protector may be operated and reset as above described, as many times as desired. If the protector is operated a great number of times it may be necessary vto apply fresh cementing material Ato the exterior surlace'of the cup 2, but this may be readily done in any suitable manner` y I do not wish to limitthis invention to the particular details of construction as herein shown. as many modi from the scope of the invention.

What l claim as my invention and desire to secure by Letters Patent is,-

l. An electro-thermal protector comprising a met: 1llic. cup, heating means contained within the cup. another v metallic cup in which the first 4mentioned cup is inserted and secured thereinlby heat-susceptible cementing materialfand a 'coil spring placed within the second mentioned cup and making electrical connection with both of the said 'cups whereby Athe circuit through the protector is kept closed when the cemented joint opens.

2. An electro-thermal protector comprising two metallic cementing 'material holding the cups together, heat-pro- .lucing means within the inner cup for softening the said tion with both of the said cups whereby the circuit through the protector is maintained closed when the cups are separated.

3. An electro-thermal -pro'tector comprising two conically shaped metallic cups, one placed within the other (so, that `the conical surfaces fit eachother and make electrical connection with each other, heat-susceptible cementing main the interior cup for softening the cementing material upon abnormal current conditions, and a coil spring placed within the -e'xter'ior cup whereby electrical *connection bctween the said cups is maintained after the protector has operated.

l. In an electrical protector 0f the character described, .two metallic surfaces bearing againstV each other, a thin l iilm of heat-susceptible non-c0nducting cementing material placed between the said metallic surfaces and cementing Contact between the two surfaces, and means for heating the said cementingl material upon abnormal current conditions tb allow the vsaid metallic surfaces to separate.

5. An electrical protector comprisingl metallic Acupshaped portions, one placed within the other und normally held together' byheat-susceptible cementing material` means for heating the cementingr material upon abnormal current conditions: and a spring within the external cup, 'placed under tension whereby the said cups are separated when the said cementlngr material is softened. 6. An electrical yprotector comprising ,metallic cupshaped portionsonevplaced withinthe other and normally held together by heat-susceptible cementing material. 'means for heating the cementing material upon nimm-mal current conditions, and 'means within the exterrval"cup whereby electrical connection is. maintained between the said vcupsl after the cemented joint is opened. -1

T. An electro-thermal protector comprising heat-producing-means, an openable lmetallic joint, and heat-susceptible non-conducting' ceme'nting material with-in the joint, all in series in the circuit, the said cementing' material being terially affect the conductivity of the s aidcircuit.

trolled, as this is well kfnown to those-familiar withy If it is desired to reset the protector for anotherV operation, the'same may be -.heated in any suitable."

y,cementing material, and means making electrical connecj same together without materially affecting the electrical and thereby hold the partsof the protector in Sci P0" Y' lications may be 'made therein without departing i -cup-shaped portions, one within the'otheri heat-susceptible terial securing the said cups together, heating means withappliediwithin the joint in a film so thinas to not ma- 8. In an electrical protector ot the character described,

a conicaily shaped metallic cup, a neat-producing elementy of homogeneous resistance material placed within tle cup under pressure and insulated from the sides thereofi a second` cup within which the first is placed and normally cemented therein, a' knob on the inner end of the rst men tioned cup, and a coil spring within the second mentioned cup, one endvof which is squeezed into the second mentioned cup and the vother end `of which is secured to the said knob, whereby the circuit'through the protector is maintained after the cups have separated upon the operation of the device.

9. In a protectory of the character described', a conically shaped metallic cup portion, an insulating shell within the cup portion, a homogeneous resistance body, a contact plate,and a terminal member all in series within the said .insulating shell, the said resistance body making electrical crates.

10. A self-contained electrical protector unit of the character described, comprising heating means and an openable metallic joint normally held against opening by heat-susccptible non-conducting cementing material, all in series in the circuit, and means Within the device whereby the circuit through the protector isjnaintained after the said cemented joint has opened.

11. An electrical protector of the character described, comprising an openable joint normally held againstl opening by heat-susceptible non-conducting cementing material,

means for softening the said cementing material upon abnormal current conditions in the device, .and means within the device adapted to maintain a circuit through the protector after same has operated.

`itter the protector op-` 12. 'An electrical protector oi! the character described, comprising an openable joint in series in the circuit, nor mally held against opening by a lm ofheat-susceptible non-conducting cementing material which is also in series in the circuit, means for heating the said cementing msterial upon abnormal electrical conditions, and a coil spring in the device placed under tension whereby the said cemented ljoint is opened upon abnormal heating.'

13. an electrical protector of the character described,

comprising ll1eatproducing means and an openable joint and means for pullig the said shell,v lportions apart when the cementing material is heated.

15. A heat-cartridge of the longitudinally operable type comprising two metallic vshell portions fitted one within the other and normally held against separation by heatsusceptible non-conducting cementing material, heating means within the device tor heating the said cementing material upon abnormal current conditions l'n the device, means for pullingl the said shell portions apart when the cementing material is heated, and means Within the protector for maintaining a closed circuit through the protector after same has operated.

As inventor of the foregoing, I hereunto subscribe my name in the presence of two subscribing'wltnesses, this 12th day of February, 1907.

FRANK B. cooK.

Witnesses FREDERICK R. PARKER, JNO. F. ToMPKINs. 

